Abstract: A relationship is developed between a discharge condition of a refrigerant leaving a compressor, and the suction superheat or refrigerant quality. By relying upon measurement and control of the discharge condition, the present invention is able to achieve very low suction superheat values. Controlling the operation to very low suction superheat values results in augmented refrigerant system performance.

Abstract: A method is provided for operating a refrigerant vapor compression system at substantially zero cooling capacity to facilitate tight temperature control within a climate-controlled environment associated with the refrigerant vapor compression system. The method includes the step of diverting substantially all refrigerant flow from the primary refrigerant flow circuit of the refrigerant vapor compression system at a first location downstream, with respect to refrigerant flow, of the heat rejection heat exchanger and upstream, with respect to refrigerant flow, of the evaporator refrigerant expansion device to reenter the primary refrigerant flow circuit at a second location downstream, with respect to refrigerant flow, of the evaporator and upstream, with respect to refrigerant flow, of the compression device.

Abstract: A refrigerant cycle is provided with an economizer circuit. The amount of refrigerant passing through the economizer circuit can be gradually modulated by an expansion device whose position can be easily adjusted from fully open to fully closed or disengaged. In the past, economizer circuits have either been fully engaged or fully disengaged. Modulation of economizer flow allows for variable capacity operation. This improves unit operating efficiency, minimizes unit cycling and prevents compressor overloading at extreme of operating conditions. It also allows for head pressure and discharge temperature control.

Abstract: A superheat control utilizes a sensor at a location downstream of an evaporator after some heat is delivered to the refrigerant. In one embodiment, the compressor is a sealed compressor with at least a portion of the refrigerant being heated by an electric motor. The temperature is sensed after the refrigerant temperature has increased after passing over the electric motor. In another embodiment, the refrigerant temperature is measured after some minimal compression and minimal temperature rise has occurred within the compressor pumping elements. In either case, by measuring the temperature of the refrigerant after some additional heat has been added to the refrigerant, the refrigerant super-heat leaving the evaporator can be controlled to a lower value. The improved superheat control enhances the system performance by increasing system efficiency, system capacity and improving oil return to the compressor.

Abstract: A pulse width modulation control is provided for a suction modulation valve in a refrigerant system. An intentional small “leakage” path is maintained through the suction modulation valve to ensure that the pressure inside the compressor shell does not decrease below a safe reliability threshold but, at the same time, does not exceed a certain value, which would cause the refrigerant system to operate inefficiently, when the pulse width modulation control has moved the suction modulation valve to a closed position. The size of this minimum “leakage” path is continuously adjusted to ensure that the optimum pressure inside the compressor shell is maintained regardless of the evaporator pressure and other operating conditions.

Abstract: A method and system for operating a refrigerant system having a reciprocating compressor with a main cylinder module and an economizer cylinder module includes regulating a flow of refrigerant into the main cylinder module and regulating a flow of refrigerant into the economizer cylinder module. The main cylinder module and the economizer cylinder module have separate inlet and outlet discharge streams. The flow through each module is regulated as a function of an operating mode of the refrigerant system, which includes various modes of loading and unloading based, in part, on a cooling demand. In some embodiments, the refrigerant system may include a connector refrigerant line configured to redirect refrigerant from the economizer cylinder module to the main cylinder module or from the main cylinder module to the economizer cylinder module.

Abstract: A variable speed electric drive for use in refrigerant systems includes an electric motor for driving an associated component at a variable speed that is a function of an operating frequency of the motor; and a control for supplying alternating discrete drive frequencies to the electric motor to provide a continuously variable speed drive of the associated component. The control cycles the drive frequency to the electric motor among the at least two discrete frequencies so that the variable average resultant speed at which the associated component is driven is a function of a combination of the selected at least two discrete frequencies.

Abstract: A heat pump is provided with an improvement while switching from heating/cooling mode to a defrost mode. Prior to initiation of a defrost mode, an electronic expansion device is moved to an open position such that refrigerant can migrate between the indoor-outdoor heat exchangers. When the operation of the defrost cycle is initiated, there is a lower likelihood and severity of flooded starts, as the refrigerant, under existing pressure differential at system shutdown, will move to the heat exchanger that will be downstream of the compressor in the defrost mode. Thus, no flooded start will occur on the subsequent compressor start-up. After completion of the defrost cycle, the electronic expansion device is again opened prior to return to operation in the conventional heating/cooling mode. In case subsequent starts are in an identical mode of operation, the electronic expansion valve is kept closed during shutdown to minimize cyclic performance losses.

Abstract: A reciprocating piston compressor for use in a refrigerant compression circuit comprises first and second intake manifolds, first and second reciprocating piston compression units, an outlet manifold and a first pulsing valve. The intake manifolds segregate inlet flow into the compressor. The first and second reciprocating piston compression units receive flow from the first and second intake manifolds, respectively. The outlet manifold collects and distributes compressed refrigerant from the compression units. The first pulsing valve is mounted externally of the first intake manifold to regulate refrigerant flow into the first intake manifold. In another embodiment, a second valve is mounted externally of the second intake manifold to regulate flow into the second intake manifold, and the first and second valves are operated by a controller. The controller activates the first valve with variable width pulses having intervals less than an operating inertia of the refrigerant compression circuit.

Abstract: A refrigerant system has a refrigerant circuit comprising a compressor for compressing a refrigerant and delivering it downstream to a condenser. A bypass line is provided around the condenser for selectively allowing at least a portion of refrigerant to bypass the condenser. Valves are provided on a line leading to the condenser and on the bypass line to individually control the flow of refrigerant. An expansion device is located downstream of the condenser, and an evaporator is located downstream of the expansion device. A reheat cycle is incorporated into the system. The reheat cycle includes a valve for selectively delivering at least a portion of refrigerant through a reheat heat exchanger, which is positioned in the path of air downstream of the evaporator. A control is provided for the system to achieve a desired level of dehumidification and temperature control to air being delivered into the environment to be conditioned.

Abstract: Multi-stage refrigerant systems operate with a lower stage compressor of a first type and a higher stage compressor of a second type. In one embodiment, the lower stage compressor type is selected to have the most beneficial characteristics at lower pressure operation, while the higher pressure stage compressor type is selected to have the most beneficial characteristics at higher pressure operation.

Abstract: The present disclosure provides a refrigerant system that comprises a compressor, a main refrigerant circuit, an economizer refrigerant circuit, and a bypass refrigerant circuit. The refrigerant system further comprises a single refrigerant flow control device switching between different operational modes to provide various degree of system unloading in operation. The present disclosure also provides a method of operating the refrigerant system.

Abstract: A refrigerant cycle is provided with a multi-port compressor or compressor stages connected in series, and multiple condensers. A single evaporator communicates with the plurality of condensers. At least one of the plurality of condensers receives fully compressed refrigerant while the other condensers receive refrigerant at intermediate pressure. A control can optionally direct refrigerant to the condensers to achieve desired system heat rejection characteristics and operating conditions. One or multiple reheat coils may be associated with the evaporator and are arranged either in series or in parallel to provide a desired dehumidification function and reheat stages. One or several of the intermediate pressure condensers may be utilized for the reheat function as well.

Abstract: A heat pump refrigerant system has a compressor for delivering a compressed refrigerant to a reversing refrigerant flow control device. The reversing refrigerant flow control device selectively delivers refrigerant to an outdoor heat exchanger in a cooling mode of operation, and to an indoor heat exchanger in a heating mode of operation. Refrigerant from an outdoor heat exchanger passes through an expansion device to an indoor heat exchanger in a cooling mode, and from the indoor heat exchanger through an expansion device and to the outdoor heat exchanger in a heating mode. A reheat circuit includes a reheat heat exchanger positioned to be in the path of air delivered over the indoor heat exchanger and into an environment to be conditioned. The reheat heat exchanger and outdoor heat exchanger both are provided by microchannel heat exchangers.

Abstract: A modular multi-channel tube heat exchanger includes a plurality of aluminum heat exchanger modules selectively connected in fluid communication by interconnecting tubing. Each heat exchanger module includes an aluminum inlet header, an aluminum outlet header and a plurality of aluminum heat exchange tubes extending longitudinally therebetween. Each of the plurality of heat exchange tubes may have a plurality of flow paths extending longitudinally in parallel relationship from an inlet end thereof in fluid communication with the inlet header to an outlet end thereof in fluid communication with the outlet header.

Abstract: A microchannel heat exchanger has at least two manifolds, with the at least two manifolds communicating with a respective one of a first and second plurality of heat exchange tube banks. The first and second plurality of heat exchange tube banks are intertwined within a single microchannel heat exchanger core.

Abstract: A refrigerant system operates in an environment defined by three distinct temperature levels, such as, for instance, the outdoor ambient temperature level, the indoor temperature level and the refrigeration temperature level. The refrigerant system is provided with an air-to-refrigerant heat exchanger located within the general indoor environment and connected to receive the flow of refrigerant from a heat rejection heat exchanger. The air-to-refrigerant heat exchanger gives off heat to the indoor air and in the process further cools the refrigerant flowing to an expansion device to thereby increase the cooling effect provided by an evaporator to the refrigeration area. Provisions are also made to partially or entirely bypass the air-to-refrigerant heat exchanger and/or the heat rejection heat exchanger, on a selective basis.

Abstract: A refrigerant vapor compression system includes a compression device, a refrigerant heat rejection heat exchanger, an expansion device, and a refrigerant heat absorption heat exchanger disposed in a closed-loop refrigerant circuit in serial refrigerant flow relationship. A refrigerant storage device is connected by at least one refrigerant line in fluid communication with the refrigerant circuit and a flow control device interdisposed in that refrigerant line. Refrigerant may be selectively withdrawn from and returned to the high-pressure side of the refrigerant circuit; or withdrawn from and returned to the low-pressure side of the refrigerant circuit; or withdrawn from the high-pressure side of the refrigerant circuit and returned to the low-pressure side of the refrigerant circuit. The refrigerant may be withdrawn from and returned to the refrigerant circuit during operation or during an off-cycle.

Abstract: A transport refrigeration/air conditioning system includes a fuel cell which is electrically connected to at least one of the compressor drive motor, evaporator fan motor or condenser fan motor to provide electrical power thereto.

Abstract: An evaporator includes a manifold receiving a distributor insert. The distributor insert receives the flow of refrigerant to be delivered into the manifold, and has openings to communicate this refrigerant into a plurality of chambers which are defined between adjacent dividing elements of the distributor insert within the manifold. In this manner, these chambers are each associated with distinct heat transfer tubes and such that these chambers are isolated from each other.